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Search Results: 1 - 10 of 1986 matches for " 衡亚洲 "
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非均匀Winkler弹性地基上变厚度矩形板自由振动的DTM求解 Free vibration analysis for rectangular plates with variable thickness resting on a non-uniform Winkler elastic foundation by DTM
Free vibration analysis for rectangular plates with variable thickness resting on a non-uniform Winkler elastic foundation by DTM

滕兆春,亚洲,刘露
- , 2018, DOI: 10.7511/jslx20170217002
Abstract: 针对非均匀Winkler弹性地基上变厚度矩形板的自由振动问题,通过一种有效的数值求解方法——微分变换法(DTM),研究其量纲固有频率特性。已知变厚度矩形板对边为简支边界条件,其他两边的边界条件为简支、固定或自由任意组合。采用DTM将非均匀Winkler弹性地基上变厚度矩形板量纲化的自由振动控制微分方程及其边界条件变换为等价的代数方程,得到含有量纲固有频率的特征方程。数值结果退化为均匀Winker弹性地基上矩形板以及变厚度矩形板的情形,并与已有文献采用的不同求解方法进行比较,结果表明,DTM具有非常高的精度和很强的适用性。最后,在不同边界条件下分析地基变化参数、厚度变化参数和长宽比对矩形板量纲固有频率的影响,并给出了非均匀Winkler弹性地基上对边简支对边固定变厚度矩形板的前六阶振型。
For free vibration problem of rectangular plates with variable thickness resting on a non-uniform foundation and by an effective solving numerical method called differential transformation method (DTM),the dimensionless natural frequency characteristics are investigated.Two opposite edges of plates are assumed to be simply supported and other two edges can be changed into simply supported,camped or free boundary conditions arbitrarily.By using DTM,dimensionless normalized governing differential equation of rectangular plates with variable thickness resting on a non-uniform Winkler elastic foundation and boundary conditions are transformed to the equivalent algebraic equations,which can derive equations of dimensionless natural frequency.The example results are back to cases for uniform Winkler rectangular plates and rectangular plates with variable thickness,which are compared with different methods in present literature.The result shows that DTM have very higher accuracy and stronger applicability.Finally,the influence of the varied foundation parameter,the varied thickness parameter and the aspect ratio on dimensionless natural frequencies are analyzed for different boundary conditions and deriving the first six mode shapes for CSCS plate with variable thickness resting on a non-uniform Winkler elastic foundations.
变刚度Winkler地基上受压非均质矩形板的自由振动与屈曲特性
滕兆春,亚洲,,,,
- , 2019,
Abstract: 基于经典薄板理论,利用Hamilton原理建立变刚度Winkler地基上受压非均质矩形板自由振动与屈曲问题的控制微分方程并进行无量纲化。通过一种半解析方法?微分变换法(DTM)研究其无量纲固有频率和屈曲临界载荷特性。首先采用DTM将其无量纲控制微分方程及边界条件变换为等价的代数方程,得到含有频率和屈曲载荷的特征方程。再将该问题退化为面内变刚度矩形板情形,其DTM解与精确解进行对比,结果表明DTM具有非常高的精度和很强的适用性。最后计算出在不同边界条件下屈曲临界载荷并分析地基刚度变化参数、弹性模量变化参数、密度变化参数、面内载荷和长宽比对矩形板无量纲固有频率的影响,给出了不同边界条件下变刚度Winkler地基上受压非均质矩形板的前三阶振型。
Abstract:Based on the classical thin plate theory, the governing differential equation of free vibration and buckling of a compressed non-homogeneous rectangular plate on Winkler foundation with variable stiffness was established by using Hamilton’s principle, and then its dimensionless form was obtained.The characteristics of the plate’s dimensionless natural frequencies and buckling critical loads were studied with a semi-analytical method called the differential transformation method (DTM).DTM was used to convert dimensionless governing differential equation and boundary conditions into equivalent algebraic equations, and derive characteristic equations of frequencies and buckling loads.Then, the problem was degenerated into the case of an in-plane variable stiffness rectangular plate, and its DTM solution was compared with the analytical solution.The results showed that DTM have very higher accuracy and stronger applicability.Finally, the buckling critical loads were calculated under different boundary conditions, and the effects of foundation stiffness parameters, elastic modulus parameters, density parameter, in-plane loads and length-width ratio on the plate’s dimensionless natural frequencies were analyzed.The first three modal shapes of the compressed non-homogeneous rectangular plate on Winkler foundations with variable stiffness were deduced under different boundary conditions.
弹性地基上转动FGM梁自由振动的DTM分析 DTM analysis for free vibration of rotating FGM beams resting on elastic foundations
DTM analysis for free vibration of rotating FGM beams resting on elastic foundations

滕兆春,亚洲,张会凯,马永斌
- , 2017, DOI: 10.7511/jslx201706006
Abstract: 基于Euler-Bernoulli梁理论,利用广义Hamilton原理推导得到弹性地基上转动功能梯度材料(FGM)梁横向自由振动的运动控制微分方程并进行量纲化,采用微分变换法(DTM)对量纲控制微分方程及其边界条件进行变换,计算了弹性地基上转动FGM梁在夹紧-夹紧、夹紧-简支和夹紧-自由三种边界条件下横向自由振动的量纲固有频率,再将控制微分方程退化到转动和地基时的FGM梁,计算其不同梯度指数时第一阶量纲固有频率值,并和已有文献的FEM和Lagrange乘子法计算结果进行比较,数值完全吻合。计算结果表明,三种边界条件下FGM梁的量纲固有频率随量纲转速和量纲弹性地基模量的增大而增大;在一定量纲转速和量纲弹性地基模量下,FGM梁的量纲固有频率随着FGM梯度指数的增大而减小;但在夹紧-简支和夹紧-自由边界条件下,一阶量纲固有频率几乎不变。
Based on Euler-Bernoulli beam theory,the governing differential equation of motion of the lateral free vibration a rotating functionally graded material (FGM) beam on elastic foundation is derived by using generalized Hamilton principle,and differential transform method (DTM) is used to transform the dimensionless governing differential equation and the boundary conditions.At the same time,the dimensionless natural frequencies of transverse free vibration of rotating FGM beam on elastic foundation at the clamped-clamped,clamped-simply supported and clamped-free three boundary conditions are determined,then the governing differential equation is degenerated to the FGM without rotation and elastic foundation.The values of first non-dimensional natural frequency with different FGM gradient index are calculated and they are completely consistent with the results by either the FEM or the Lagrange multipliers method in the literature.The results show:at the above three kinds of the boundary conditions,the dimensionless natural frequencies increase with the growth of the dimensionless rotating speed and the dimensionless elastic foundation modulus.Under a certain dimensionless rotating speed and dimensionless elastic foundation modulus,the dimensionless natural frequencies decrease along with the growth of the FGM gradient index.However,when at clamped-simply supported and clamped-free boundary conditions,the first dimensionless natural frequency is almost constant.
南京前中央地質調查所近訊

科学通报 , 1950,
Abstract: 中央地質調查所胚孕於一九一二年,正式成立於一九一六年,已有三十五年的歷史。一九四九年四月二十三日南京解放之前,該所絕大多數人員,堅定的保護着公物,靜待解放。所有圖書、儀器完全無缺的變爲人民財產,這是值得慶幸的。因該所領導問題未能即時解决,在一九四九年的大半年中,陷入保管狀態,除在南京附近作一些短期調查與整理過去的研究調查資料外,工作未能大量開展。今年二月間,中央財經會邀集各地質機關授予調查東北、華北及中南各區的地質鑛產調查工
南京前中央地質調查所近訊

科学通报 , 1950,
Abstract: 中央地質調查所胚孕於一九一二年,正式成立於一九一六年,已有三十五年的歷史。一九四九年四月二十三日南京解放之前,該所絕大多數人員,堅定的保護着公物,靜待解放。所有圖書、儀器完全無缺的變爲人民財產,這是值得慶幸的。因該所領導問題未能即時解决,在一九四九年的大半年中,陷入保管狀態,除在南京附近作一些短期調查與整理過去的研究調查資料外,工作未能大量開展。今年二月間,中央財經會邀集各地質機關授予調查東北、華北及中南各區的地質鑛產調查工作,该所人员负担了大部任务。
我国自然资源利用现状和对策
亚洲
资源科学 , 1994,
Abstract: 自然资源是人类生存与发展的物质基础。我国是资源大国,但按人均占有量计,又可称资源小国。人口增长、经济发展与资源供给始终是最基本的矛盾。本文分析了我国主要自然资源态势、开发利用现状,主张建立资源节约型国民经济体系的战备思想和7项基本对策。
与风电并网相关的研究课题
亚洲
电力系统自动化 , 2003,
Abstract: 风力发电环境友好、技术成熟、可靠性高、成本低且规模效益显著,是发展最快的新型能源。很多与大型风电场并网运行有关的技术课题亟待解决,例如,大型风电场并网会改变系统原有的潮流及网损的分布,对电网的规划提出了新的要求;可能给配电网带来电能质量问题,如谐波污染、电压波动及闪变;对系统的功角、频率以及电压稳定性产生不利影响;风电具有很强的随机性,需要研究能够考虑风电特点的发电和运行计划方法;重新评估系统的发电可靠性,分析风电的容量可信度;研究新的无功调度及电压控制策略等。感应发电机因为结构简单、并网方便,一度成为风力发电机组的首选,很多研究也是基于这样一个事实。随着电力电子元件的性价比不断提高,采用同步电机、双馈电机等新型发电机组是大势所趋,风电场可以像常规机组一样,承担电压及无功控制的任务,出现了许多新的富有挑战性的研究课题。风力发电作为电力系统中一个崭新的领域,正吸引越来越多的研究机构和人员从事风电并网技术的研究和咨询工作。
我国农村家政养老服务模式研究
亚洲
湖南工业大学学报(社会科学版) , 2014,
Abstract: 家政养老服务模式是社会化养老的一个重要方面。在农村发展家政养老服务模式可以满足巨大的养老需求,提高养老质量,带动就业和促进农村经济发展。但也存在着一定的障碍,如传统养老观念的束缚,法律法规的不健全,硬件条件的限制和家政养老服务机构或企业经营管理的不规范等。需要个人、社会和政府采取相应的对策和措施,如转变养老观念,加强农村家政养老方面法律法规的建设,加大政府政策扶持的力度和加强农村家政服务机构或家政公司自身的建设。
基于GM(1,n)模型的铝需求预测
亚洲
金属矿山 , 2012,
Abstract: 科学预测产品需求可以指导产业调整和行业发展。灰色理论能够减少对信息量少的系统进行主观臆断。铝的需求影响因素主要包括经济社会发展、产业结构、资源替代、再生铝利用、政策因素和资源供给等。采用GM(1,n)模型,预计2015年GDP增长率约8%,原铝消费量2350~2870万t,相应需要铝土矿约9000万t。预测值通过精度检验,等级最高。分析表明,预测结果合理。
黄河大堤加高培厚工程中的测量问题
亚洲
人民黄河 , 2000,
Abstract: ?贯穿于黄河大堤加高培厚工程建设始终的、重要而又属基础性的工序--工程测量,却在设计、施工、验收三个阶段中被轻视。针对工程测量在三个阶段中的现状,结合有关规范、规程和实例,分析其危害性,并提出规范性做法,以引起各级领导和工程技术人员的重视。
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